Advice for first time rolling

Hey all, I’m going to a rave on Saturday and this will be my first time rolling. I get pretty nervous trying any new drugs now after I had a pretty bad acid trip a few years ago, but from what I’ve seen Molly seems to be a lot more similar to a stimulant than a psychedelic, which I have no issues with. I’m looking for any advice on how to have the safest and most enjoyable roll…How much should I take for a first dose? Anything I should do to prep? Should I bring a bit of Xanax for the comedown? Thanks for any tips!!